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Plug-in hybrid cars emit almost 5x more planet-heating emissions than official figures show, as per a recent report.

Widening Gap In Official and Real-World Emissions

Data reveals that PHEVs emit only 19% less CO₂ than conventional gas and diesel vehicles, based on research carried out by a non-profit group. That contrasts sharply with laboratory tests, which suggested a three-quarters decrease in pollution.

Researchers studied information from in-vehicle energy use meters of 800,000 vehicles registered in Europe between 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab estimates, up from three and a half times in 2021.

“Real-world emissions are increasing, while official figures are falling,” said a lead researcher participating in the study. “This discrepancy is widening and poses a serious problem. As a result, PHEVs emit nearly as heavily as petrol cars.”

Key Reasons Behind the Emissions Gap

Researchers attributed most of the difference to overestimates of the “utility factor” – the ratio of kilometers driven in battery mode relative to overall distance. They found that only 27% of driving was done in EV mode, whereas official estimates assumed over four-fifths.

Even, when operating in EV mode, pollution levels were well above official projections. This happened because EV motors were insufficiently powerful sufficient to function independently, leading to engines burning gasoline for almost a third of the distance covered in electric mode.

Regulatory and Financial Consequences

According to estimates, the underestimation of PHEV emissions allowed four large carmaker companies to escape more than €5bn in fines from 2021 and 2023, by artificially easing adherence with European Union average fleet CO₂ targets.

Furthermore, owners of PHEVs would spend approximately €500 extra annually in operating costs than is assumed under lab tests.

“The strong claims that manufacturers like to make about their PHEV cars are clearly far from the mark,” commented a transport expert. “Consumers are being misled into thinking that by buying a PHEV, they are benefiting the environment and saving costs. Actually, PHEVs are only slightly improved than regular petrol and diesel cars in terms of energy consumption, CO₂ emissions, and operating costs.”

Policy Discussion and Industry Pressure

Hybrid cars have lately been drawn again into political debates as automakers have pressed the EU to weaken CO₂ standards. A proposed ban on new internal combustion cars in 2035 has faced intense pressure from the car industry and resistance from EU countries with significant automotive industries.

Several senior politicians have suggested PHEVs as a possible “flexibility” solution to introduce in the legislation.

One independent energy economics expert, who was not involved with the study, called the analysis a “highly valuable addition” after years in which parts of the automotive sector claimed there was insufficient data to properly evaluate real-world emissions.

“These findings show, beyond any doubt, that the difference between lab and real-world PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or diesel cars,” the expert said. “Any regulatory adjustments regarding PHEVs should be made with extreme caution and considering that evidence.”